The planted tank hobby is like any other hobby -- people get into it for different reasons. And those reasons can range from a whim like "I saw one on the internet and it seemed cool " to a more serious "I'm an aquatic botanist, I love aquatic plants and I want to experiment". So on the whim end of the spectrum, a person may not be as emotionally, mentally or intellectually invested and thus doesn't have an anchor that keeps them tethered to the hobby, especially when they face challenges. On the serious end, a person likely has way more invested, and therefore is more likely to stick with it through the tough times. And that person probably does more upfront investigation anyway that helps them avoid a lot of the more common pitfalls that lead to frustration.
The other thing is personality. Again, there is that spectrum... on one end is the type who starts and stops a lot of things. Someone who gets frustrated easily, who gives up when the answer is not spelled out for them, who doesn't have patience. Someone who wants instant gratification. On the other end is the type who starts something, solves problems, delves a little deeper, challenges themselves, and takes their hobby one step further, whether that means increasingly challenging setups, or adding more and more tanks. They have patience and like to think. And of course there are personalities all along that spectrum.
If you combine the reasons for why a person got into the hobby with their personality, you can probably guess the likeliness of them leaving the hobby.